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A367007 Number of distinct prime factors of n*2^n + 1. 4
0, 1, 1, 1, 2, 2, 3, 3, 2, 2, 3, 2, 3, 2, 3, 3, 2, 3, 4, 4, 3, 2, 4, 4, 4, 4, 4, 4, 2, 3, 5, 5, 3, 2, 5, 2, 3, 3, 3, 3, 3, 4, 4, 5, 4, 4, 5, 5, 4, 2, 6, 3, 6, 3, 5, 4, 3, 5, 5, 4, 4, 7, 3, 3, 6, 5, 7, 4, 4, 5, 5, 5, 5, 5, 3, 5, 4, 4, 4, 6, 4, 4, 4, 5, 4, 6, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,5
COMMENTS
The numbers n*2^n+1 are called Cullen numbers.
LINKS
FORMULA
a(n) = omega(n*2^n + 1) = A001221(A002064(n)).
MATHEMATICA
Table[PrimeNu[n*2^n + 1], {n, 0, 100}] (* Amiram Eldar, Jan 06 2024 *)
PROG
(PARI) a(n) = omega(n*2^n + 1); \\ Amiram Eldar, Jan 06 2024
CROSSREFS
Sequence in context: A055092 A213202 A234972 * A130326 A059906 A349196
KEYWORD
nonn
AUTHOR
Sean A. Irvine, Oct 31 2023
STATUS
approved

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Last modified February 29 09:21 EST 2024. Contains 370418 sequences. (Running on oeis4.)